1. Field of the Invention
The present invention relates to a grinding wheel for use in a grinding apparatus for grinding various materials such as brick, concrete, granite, marble, etc., and more particularly to a grinding wheel having dust discharge-impelling blades capable of impelling to discharge the dust produced during grinding operation to the dust collection machine to decrease dispersing the dust in the air, and increase cooling efficiency of the grinding wheel, thereby enhancing the grinding ability and the life of the grinding wheel.
2. Background of the Prior Art
Conventional grinding wheels 90 and 100 for use in grinding apparatus comprise plate type shanks 91 and 101 connected with a shaft of electric motor, and grinding tips 92 and 102 disposed fixedly in single or double circumferential array on shanks 91 and 101 by means of welding or joining, as shown in FIGS. 11 and 12.
Grinding tips 92 and 102 are fabricated by mixing particles of diamond or grinding materials, particles of metals composing of cobalt, nickel, bronze, copper, etc., or particles of resin or ceramic and forming a given shape out of the mixed particles by plastic working including press work.
On the shanks 91 and 101, there is a plurality of round shape holes 93 and 103 for discharging grinding particles or dusts produced during grinding operation through the dust inlet portion or the hood of a dust collection machine which is disposed on the shanks 91 and 101. Numerals 94 and 104 are rim portions.
In operation, the grinding wheels 90 and 100 are rotated at a high speed of about 10,000 RPM to let the grinding tips 92 and 102 to grind the materials in velocity of about 70 to 80 m/sec, and thereby the produced grinding particles or dust is carried with the centrifugal force corresponding to the moving velocity of the grinding tips 92 and 102 and inducted through the round shape holes 93 and 103 into the dust collection machine usually having air induction or wind velocity of about 25 to 30 m/sec and flux of about 1,000 to 1,300 l/minute when the diameter of a dust collection tube thereof is 30 mm.
However, at this time, since the air induction velocity of the dust collection tube of the dust collection machine is slower than the moving velocity of the grinding tips as noted above, i.e., the air induction force of the dust collection machine is smaller than the centrifugal force of grinding particles or dust, a large amount of grinding particles or dust was leaked out beyond the limits of the dust inlet portion of the dust collection machine disposed on the grinding wheels 90 and 100 for guiding dust to the dust collection tube of the dust collection machine, and dispersed in the air to give rise to the bad effect to users' health and the contamination of environment.
Further, since the air induction velocity for inducting dust into the dust collection tube of the dust collection machine is abruptly decreased to about 2 m/sec at a lower surface of the grinding tips 92 and 102, i.e., a surface of materials, it was almost impossible to improve the dust dispersing problem only by increasing the wind velocity of the dust collection machine.
Also, since the grinding tips 92 and 102 are cooled only by air circulation, the grinding tips 92 and 102 located in the position which air induction velocity is abruptly decreased, was-easily carbonized or oxidized and thereby defaced by friction heat between the materials and the grinding tips during the continuous grinding operation for a long time to induce poor grinding and decrease the grinding efficiency and the life of the wheel.